(i) Field of the Invention
This invention relates to a pumping unit and a method of pumping; more especially the invention is concerned with an oil pumping unit and a method of pumping oil.
(ii) Description of the Prior Art
Pumping units for pumping oil and oil and water mixtures from underground sources are known, and function to vertically reciprocate a sucker rod in a bore or drill hole. In the down-stroke the unit is aided by gravity, in the up-stroke which is the working stroke, greater work is required to overcome gravity. Thus the power requirement is greater on the up-stroke than on the down-stroke.
One widely used pumping unit has a heavy cantilever weight which assists in the up-stroke, however, this means that the cantilever weight must be raised during the down-stroke, thereby necessitating the use of greater power in the down-stroke.
Existing pumping units have no means for readily varying different parameters such as the rate of pumping and the length of stroke.